Wendell Garrett poses in this undated photo. Garrett, an authority on American decorative arts known to public-television viewers for his long, professorial presence as an appraiser on “Antiques Roadshow,” died Wednesday in Williston. He was 83.

Wendell D. Garrett, an authority on American decorative arts known to public-television viewers for his long, professorial presence as an appraiser on “Antiques Roadshow,” died Wednesday in Williston. He was 83.

His former wife Elisabeth Garrett Widmer confirmed the death.

The author or editor of many books on antiques and Americana, Garrett was known through his writings, TV appearances and frequent lectures as an erudite democratizer, mediating between the rarefied world of antiques and a wide public.

He appeared on every season of the American version of “Antiques Roadshow” from its inception in 1997 through the new season, filmed last summer and having its premiere Jan 7.

Garrett also had long associations with Sotheby’s, where he was a retired senior vice president in the American decorative arts department, and with The Magazine Antiques, as the publication is formally known, where he was for many years the editor and publisher.

Produced by WGBH in Boston and broadcast nationwide, “Antiques Roadshow,” like the British series on which it is modeled, sends antiques experts into towns throughout the country, where residents line up to have the treasures from their attics identified and appraised.

Garrett was familiar for his white hair, impeccable suits, courtly manner and the wheelchair in which he sat: he had had a form of muscular dystrophy since the age of 19, and by the time he was in his 60s, walking had become difficult.

On the air, he advised supplicants about a welter of objects. Among them were an iridescent glass candy dish marked “L.C.T.” (the initials turned out to stand for Louis Comfort Tiffany; Garrett appraised the dish at $500 to $1,000); a mid-19th-century “pie safe,” for storing baked goods ($5,000 to $7,000); and a circa-1800 “bottle case,” for storing spirits ($30,000 to $50,000).

Garrett’s books include “Classic America: The Federal Style & Beyond” (1992); “Monticello and the Legacy of Thomas Jefferson” (1994); and, with David Larkin and Michael Webb, “American Home: From Colonial Simplicity to the Modern Adventure” (2001).

Wendell Douglas Garrett was born in Los Angeles on Oct. 9, 1929. He entered the University of California, Los Angeles, planning to become a doctor. Then organic chemistry happened. Young Garrett switched to history, receiving a bachelor’s degree.

From the University of Delaware, he earned a master’s degree in what is now the Winterthur Program in American Material Culture. He later received a master’s in American history from Harvard.

In 1959, Garrett joined the staff of the Adams Papers project, a gargantuan undertaking of the Massachusetts Historical Society. Begun in 1954, the project seeks to edit and issue letters, journals and other papers written and received by President John Adams; his wife, Abigail; and their descendants. Published by Harvard University Press and now comprising some 50 volumes, the papers are also available in a digital edition at masshist.org/publications/apde.

For the project, Garrett was an assistant editor on “Diary and Autobiography of John Adams” (1961), a four-volume work edited by L.H. Butterfield.

In 1965, while combing the archives of the Vermont Historical Society, Garrett came upon still-earlier entries from Adams’ diaries, beginning in 1753. (In the four-volume work, the diary begins in 1755.)

“The Earliest Diary of John Adams,” edited by Garrett and Marc Friedlaender under Butterfield’s supervision, was published by Harvard in 1966. That year, Garrett joined The Magazine Antiques, where at his death he was editor at large.

Garrett’s first marriage, to Jane Nuckols, ended in divorce, as did his second, to Widmer. He is survived by a brother, Ronald; three children from his marriage to Widmer, Nathaniel, Maria Garrett Lievano and Abigail Garrett Looft; and four grandchildren.

Throughout his work, Garrett voiced the conviction that antiques should never be considered in a vacuum. They were tangible manifestations of the ethos of their time and place, he said, and as such — whether cups and saucers or entire buildings — could be windows onto American social history.

By way of example, Garrett, in an interview with The Chicago Tribune in 1992, invoked the Federal style:

“I like its chaste, attenuated look — those tall, narrow proportions. That look attracts me. But intellectually, this is from the houses of our founding fathers. It reflects the order of Jefferson. They say he placed his house as he placed his mind, on a high elevation. These pieces are more than art or aesthetics; they reflect the intellectual mix of that generation.”